This is a really awesome game but it also has it's down side.
1) Video: I think that the video quality of the game is the best thing about it. I for one have never played a game with better graphics and attention to detail then this game. It might just be me but either way the games visuals are amazing. 10/10 video
2) Audio: This game has a great cast of voice actors and a beautiful soundtrack overall so it takes 10/10 for audio.
3) AI enemies: Well here is where the game gets a few points cut out. The AI enemies are pretty easy to kill because they seem a tad weaker than in the first game of the series, they also inflict less damage and hit you way harder than in the first Mass Effect game. You also always magically encounter a cover area whenever some enemies are about to appear which kinda spoils it for the player of the game because after playing the game for a while you kinda get bored of knowing when you are going to be attacked. Again this might be just me but I'd like to be surprised when I'm attacked or at least have few places to hide at that moment. So for the AI enemies and annoyingly many cover areas the game gets a 5/10.
4) AI party members. On this level I have to say that Mass Effect 2 shows a great improvement from the prequel. You can control your party members much easier as you have better options to do so. So for this improvement the game gets 10/10. Also I should mention that the party members help you while being attacked so that also adds to the 10 score here.
5) Game bugs: After playing this game again I have to say that it has improved from the first game of the series. I experienced lass game crashes or technical hangs. The only notable problems where a few bad collisions with party members while on the ship - so no big deal. 9/10 for game bugs.
6) User experience. I believe that Mass Effect 2 has a few down sides when compared to the first game because you have less options than you had in the previous game where you could upgrade each weapon with all sorts of poison damage upgrades and so on. It is rather boring to always stumble upon a cover area before being attacked by AI enemies. The planet mining system for resources is kinda boring and annoying because it takes up a while of you game time to do the mining which is necessary for the player if he wants to finish the game as he will need all kind of resources to upgrade the ship and all. I have to admit that the story and the great graphics do help the player immerse himself in the game rather well. So the game gets a 7/10 for the user experience.
7) To sump up I think this game has a great story and is a great sequel to the first Mass Effect game - it has awesome graphics, brilliant sounds, but it also has annoying mining planets thingy, all those cover areas that are seen a mile away, you don't have all those upgrades to add to weapons and armors,etc.
In conclusion I believe that this game is worth playing and in my book it is a 9/10 for all the game qualities that I look for (especially a good story)